1. Field of the Invention
The present invention concerns a method in order to generate an image data set with a magnetic resonance system. Moreover, the present invention concerns correspondingly designed magnetic resonance system as well as a corresponding electronically readable data storage medium.
2. Description of the Prior Art
Magnetic resonance tomography offers new fields of application via an acquisition of MR data with very short echo times (<500 μs). It is thereby possible to show substances or tissue which cannot be shown by means of conventional sequences—for example a (T)SE sequence (“(Turbo) Spin Echo”) or a GRE sequence (“Gradient Echo”)—since their T2 time is markedly shorter than the echo time, and thus a corresponding signal from these substances or tissues has already decayed at the point in time of the acquisition. For example, with echo times which lie within the range of the corresponding decay time it is possible to show bones, teeth or ice in an MR image although the T2 time of these objects lies in a range from 30-80 μs.
Sequences are known that enable a very short echo time. In addition to the radial UTE sequence (“Ultrashort Echo Time”), there is the approach to scan k-space in points with the free induction decay (FID) being detected. Such a method is also designated as single point imaging since essentially only one raw data point in k-space is acquired per RF excitation.
One example of such a method for single point imaging is the RASP method (“Rapid Single Point (RASP) Imaging”, O. Heid, M. Deimling, SMR, 3rd Annual Meeting, Page 684, 1995). According to the RASP method, a raw data point whose phase was coded by gradients is read out at a fixed point in time after the RF excitation relative to the echo time TE. The gradients are modified by means of the magnetic resonance system for each raw data point or measurement point, and thus k-space is scanned point by point as is shown in FIGS. 1a and 1b. 